Problem w/ my GK Backline 112 combo

Hello, I have a GK Backline 112 combo amp and just started having some issues with it. Heres the problem...

It will be working fine, and then while I'm playing I will all of a sudden lose all sound but the amp will still be on showing that it has power. When I turn it off after it does this, I hear a loud "pop" sound. Same sound usually happens when I turn it back on. Then it will randomly start working again sometimes.

Anybody have any ideas? Ive never messed with the amp or done anything to it. Use it in one location about two-three times a week for 30-minutes at a time usually. Thanks!